Squamous Cell Carcinoma (and Variants)

 Malignant epithelial tumor of squamous keratinocytes






Etiology/Pathogenesis




• Most cases are related to UV radiation

• Previous radiation therapy implicated in some cases; usually associated with more aggressive SCC


Clinical Issues




• Often arises in sun-damaged skin of elderly patients (usually head and neck)
image Vast majority of cases associated with preexisting actinic keratosis (AK)

• Complete surgical excision is optimal and definitive therapy

• Prognosis usually good in superficial and well-differentiated cases

• Worse prognosis with poorly differentiated, deeply invasive, or aggressive subtypes


Microscopic




• Proliferation of invasive atypical keratinocytes, often with areas of keratinization (keratin pearls) and squamous eddies

• Cells are present in nests, sheets, and cords

• Cytologically, cells show abundant eosinophilic cytoplasm and large nucleus with vesicular chromatin and prominent nucleoli

• Degree of differentiation is variable, ranging from well to moderately to poorly differentiated

• Multiple variants of differing malignant potential described


Top Differential Diagnoses




• Basal cell carcinoma

• Atypical fibroxanthoma

• Poorly differentiated carcinoma (Including metastatic)

• Pseudoepitheliomatous hyperplasia

• Keratoacanthoma

image
Clinical Photograph of Squamous Cell Carcinoma
Clinical photograph shows an extensive squamous cell carcinoma (SCC) arising on the distal foot in a patient with a history of previous burn injury. (Courtesy S. Yashar, MD.)


image
Invasive, Well-Differentiated Squamous Cell Carcinoma
Invasive, well-differentiated SCC is seen arising in association with an actinic keratosis image.

image
Invasive, Well-Differentiated Squamous Cell Carcinoma on Ear
Invasive, well-differentiated SCC of the ear invading up to image (but not into) the auricular cartilage is shown.

image
Moderately Differentiated Invasive Squamous Cell Carcinoma
Moderately differentiated invasive SCC shows prominent keratin pearls image and a sclerotic stroma with scattered inflammatory cells.


TERMINOLOGY


Abbreviations




• Squamous cell carcinoma (SCC)


Synonyms




• Sarcomatoid carcinoma (spindle cell carcinoma/carcinosarcoma/metaplastic carcinoma)

• Acantholytic (adenoid/pseudoglandular) SCC

• Verrucous carcinoma: Well-differentiated variant

• Keratoacanthoma (KA): Very well-differentiated variant, regresses spontaneously

• Epidermoid carcinoma


Definitions




• Malignant tumor of squamous keratinocytes


ETIOLOGY/PATHOGENESIS


Environmental Exposure




• Most cases are related to UV radiation
• Some cases are likely related to chronic inflammation (i.e., SCC arising in burns, lupus, lichen planus)

• Previous radiation therapy is implicated in some cases; usually associated with more aggressive SCC

• Chronic wounds and burn scars also can be associated with high-risk SCC

• Human papillomavirus is associated with some cases

image Especially verrucous carcinoma (low grade) and SCC in immunosuppressed patients (high grade)


CLINICAL ISSUES


Epidemiology




• Age
image Usually in elderly, especially solar-related lesions

image However, can present in wide age range (34-95 years)

– Rare cases in children (should prompt genetic studies)

• Sex
image Slightly more common in males, overall


Presentation




• Slow-growing papular, nodular, or plaque lesion
• Often arises in sun-damaged skin (head and neck tumors)

image Vast majority of cases associated with preexisting actinic keratosis (AK)

• May be ulcerated or bleeding

• Ear canal and middle ear tumors may present with pain, hearing loss, and discharge


Treatment




• Surgical approaches
image Complete surgical excision is optimal and definitive therapy

– Mohs surgery has been shown to be highly effective for most tumors

• Drugs
image If patients are not surgical candidates, topical chemotherapeutics or immunomodulators may be used

• Radiation
image May be used for very advanced cases where surgical therapy is not curative


Prognosis




• Usually excellent in most cases
• Worse prognosis with poorly differentiated, deeply invasive, or rare aggressive subtypes

• Site of tumor important for prognosis

image Lip and ear tumors more aggressive, regardless of degree of differentiation


MACROSCOPIC


General Features




• Papular to nodular or plaque-like lesion; can be exophytic
image May be ulcerated or hemorrhagic


Size




• Variable; can be small or large lesions


MICROSCOPIC


Histologic Features




• Proliferation of atypical keratinocytes invading into dermis
image Cells are present in nests, sheets, and infiltrative cords

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Apr 24, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Squamous Cell Carcinoma (and Variants)

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